Moderation actions must carry a reason code the seated charter lists (moderation teams E) #4880

Part of #4865 (decentralized moderation teams). Item E of the PR split. Wave 3: depends on H1.

Summary

In elected mode, every moderation action's reason code must be one the seated charter lists. This makes "what we moderate" machine-readable and gives voters an audit trail to judge a team.

Decisions implemented: D50 in #4865.

Current behaviour

ContractModerationReason { code: Option<u16>, text } in packages/rs-dpp/src/data_contract/config/moderation/reason.rs is stored as written; the code is not checked against anything (#4849 reserved it for this).

Scope

• When a contract has a seated team, a ban, suspension, deletion or warning with a code that the active charter's reasonCodes does not list is refused with a new state error. A missing code is also refused in elected mode with a seated team; interim mode and the owner and appointed kinds keep today's behaviour (unchecked).
• The check reads the active charter id from the seated team (H1) and the charter document from the system contract (C1); state reads belong in the action, not in the structure validation.
• Book chapter updated.

Depends on

• H1 (seated team with active charter id), C1 (charter with reasonCodes), D (warn carries a reason).

Tests

• Listed code accepted, unlisted code refused, missing code refused with a seated team, unchecked without one.